// Copyright 2023 The Jujutsu Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::fmt::Debug;
use std::io::Write as _;

use jj_lib::backend::BackendResult;
use jj_lib::backend::TreeId;
use jj_lib::merge::Merge;
use jj_lib::merge::MergedTreeValue;
use jj_lib::repo::Repo as _;
use jj_lib::repo_path::RepoPathBuf;

use crate::cli_util::CommandHelper;
use crate::cli_util::RevisionArg;
use crate::command_error::CommandError;
use crate::command_error::user_error;
use crate::ui::Ui;

/// List the recursive entries of a tree.
#[derive(clap::Args, Clone, Debug)]
pub struct DebugTreeArgs {
    #[arg(long, short = 'r', value_name = "REVSET")]
    revision: Option<RevisionArg>,
    #[arg(long, conflicts_with = "revision")]
    id: Option<String>,
    #[arg(long, requires = "id")]
    dir: Option<String>,
    #[arg(value_name = "FILESETS")]
    paths: Vec<String>,
    // TODO: Add an option to include trees that are ancestors of the matched paths
}

pub fn cmd_debug_tree(
    ui: &mut Ui,
    command: &CommandHelper,
    args: &DebugTreeArgs,
) -> Result<(), CommandError> {
    let workspace_command = command.workspace_helper(ui)?;
    let matcher = workspace_command
        .parse_file_patterns(ui, &args.paths)?
        .to_matcher();
    let entries: Box<dyn Iterator<Item = (RepoPathBuf, BackendResult<MergedTreeValue>)>> =
        if let Some(tree_id_hex) = &args.id {
            let tree_id =
                TreeId::try_from_hex(tree_id_hex).ok_or_else(|| user_error("Invalid tree id"))?;
            let dir = if let Some(dir_str) = &args.dir {
                workspace_command.parse_file_path(dir_str)?
            } else {
                RepoPathBuf::root()
            };
            let store = workspace_command.repo().store();
            let tree = store.get_tree(dir, &tree_id)?;
            // We can't use `MergedTree` here, since it only supports iterating from the
            // root, but we support a `--dir` option to read trees at any path.
            Box::new(
                tree.entries_matching(matcher.as_ref())
                    .map(|(path, value)| (path, Ok(Merge::normal(value)))),
            )
        } else {
            let commit = workspace_command
                .resolve_single_rev(ui, args.revision.as_ref().unwrap_or(&RevisionArg::AT))?;
            let tree = commit.tree();
            Box::new(tree.entries_matching(matcher.as_ref()))
        };
    for (path, value) in entries {
        let ui_path = workspace_command.format_file_path(&path);
        writeln!(ui.stdout(), "{ui_path}: {value:?}")?;
    }

    Ok(())
}
